tinued flame of reduction, it may be reduced likewise
to the metallic state, with the production of the same sublimate as
the above.

_Borax_ dissolves tin compounds in the flame of oxidation, and upon
platinum wire, very tardily, and in small quantity, to a transparent
colorless bead, which remains clear after cooling, and also when
heated intermittingly. But if a saturated bead, after being completely
cool, is exposed again to the flame of oxidation, at a low red heat,
the bead while cooling is opaque, loses its globular form, and
exhibits an indistinct crystallization. This is the case too in the
flame of reduction, but if the bead is highly saturated, a part of the
oxide is reduced.

_Microcosmic Salt_ dissolves the oxides in the flame of reduction very
tardily in a small quantity to a transparent colorless bead, which
remains clear while cooling. If to this bead sesquioxide of iron is
added in proper proportion, the sesquioxide loses its property of
coloring the bead, but of course an excess of the iron salt will
communicate to the bead its own characteristic color. In the flame of
reduction no further alteration is visible.

Tin-oxides combine with carbonate of soda, in the flame of oxidation
upon platinum wire, with intumescence to a bulky and confused mass,
which is insoluble in more soda. Upon charcoal, in the reduction
flame, it is easily reduced to a metallic globule. Certain compounds
of tin-oxides, particularly if they contain tantalum, are by fusion
with carbonate of soda reduced with difficulty; but by the addition of
some borax, the reduction to the metallic state is easily effected.

Tin-oxides exposed to the oxidation flame, then moistened with a
solution of cobalt, and exposed again to the flame of oxidation, will
exhibit, after having completely cooled, a bluish-green color.

EIGHTH GROUP.--MERCURY, ARSENIC.

These two metals are volatilized at a temperature lower than that of a
red heat, and produce, therefore, no reactions with borax and
microcosmic salt. Their oxides are easily reduced to the metallic
state.

(_a._) _Mercury_ (Hg).--This metal occurs in nature chiefly combined
with sulphur as a bisulphide.

It occurs still more rarely in the metallic form, or combined with
silver, selenium, or chlorine.

Mercury, in the metallic state, has a strong lustre, and is liquid at
ordinary temperatures, whereby it is distinguished from any other
metal. It freezes at 40 deg. and boils at 620